"""XLS 解析器，使用 xlrd 提取 Excel 数据并转换为 Markdown 表格格式"""

import os
from typing import List

import xlrd

from exceptions import ParseError
from parsers.base import BaseParser


class XlsParser(BaseParser):
    """XLS 解析器，遍历所有 sheet，跳过空 sheet，转 Markdown 表格"""

    def supported_extensions(self) -> List[str]:
        return [".xls"]

    def parse(self, file_path: str) -> str:
        file_name = os.path.basename(file_path)

        try:
            workbook = xlrd.open_workbook(filename=file_path)
        except Exception as e:
            raise ParseError(file_name, f"XLS 文件打开失败: {e}")

        try:
            return self._workbook_to_md(workbook)
        except ParseError:
            raise
        except Exception as e:
            raise ParseError(file_name, f"XLS 文件解析失败: {e}")

    def _workbook_to_md(self, workbook) -> str:
        """将整个工作簿转换为 Markdown"""
        sheet_parts = []

        for sheet in workbook.sheets():
            md = self._sheet_to_md(sheet)
            if md:
                sheet_parts.append(md)

        return "\n\n".join(sheet_parts)

    def _sheet_to_md(self, sheet) -> str:
        """将单个工作表转换为 Markdown 表格"""
        # 跳过空 sheet
        if sheet.nrows == 0 or sheet.ncols == 0:
            return ""

        # 第一行作为表头
        headers = [self._escape_cell(cell) for cell in sheet.row_values(0)]

        lines = [f"## {sheet.name}", ""]

        # 表头行
        lines.append("| " + " | ".join(headers) + " |")
        # 分隔行
        lines.append("| " + " | ".join("---" for _ in headers) + " |")

        # 数据行
        for row_idx in range(1, sheet.nrows):
            cells = [self._escape_cell(cell) for cell in sheet.row_values(row_idx)]
            lines.append("| " + " | ".join(cells) + " |")

        return "\n".join(lines)

    @staticmethod
    def _escape_cell(value) -> str:
        """转义单元格内容，避免破坏 Markdown 表格结构"""
        if value is None:
            return ""

        cell_str = str(value)

        # xlrd 返回的空单元格可能是空字符串
        if not cell_str:
            return ""

        cell_str = cell_str.replace("\r\n", "<br>")
        cell_str = cell_str.replace("\n", "<br>")
        cell_str = cell_str.replace("|", "&#124;")
        cell_str = cell_str.replace("`", "&#96;")

        return cell_str